Vacuum pump



A1182 28 1934- c. H. HAPGop 1,971,448

VACUUM 'PUMP Filed Aug. 7, 1928 3 Sheets-Sheet l /A i e s g /2 P? fm A 0 C Aug.28,1934. ,'C. H. HAPGOD A 1,971,448

VACUUM PUMP 3 Sheets-Sheet 2 VACUUM PUMP v Filed Aug. 7, 1928 3 Shee'ts-Sheeif.l 5

Patented Aug. 28, 1934 Cyrus Howard VACUUM PULIP Hapgood, Nutley, N. J., assignor to The De Laval Separator Company, New

York, N. Y., a corporation of- New Jersey Application August 7, 1928, Serial No. 297,950

s claims. (o1. 23o-207) l The type of vacuum pump to which the present invention is particularly applicable comprises a lhousing, a hollow rotor within and eccentric to the housing, an air inlet port to, and an` air outl let port from, the air space between rotor and housing, slidable vanes carried by the 'rotor and arranged radially to the rotor shaft and which extend into said air housing during the rotation of the rotor, a driving v shaft to which the hollow rotor is secured, and a driving pulley on the shaft. Vacuum pumps of this character are disclosed in the Leitch Patent No. 1,367,554, dated February 8, 1921, the Hall Patent No. 1,374,650, dated April 12, 1921, and

'16 patents issued to me No. 1,637,484, dated August 2, 1927, and No.

The objects of the present invention are to insure a continuous circulation of oil through the 1,684,395, dated September 18,

Y pump, the maintenance of a constant and predetermined iilm of oil within the rotor chamber, and the prevention of leakage from the interior to the exterior of the pump.

A preferred embodiment of the invention is 26 Shown in the drawings, in which- Fig. 1 is a longitudinal sectional view of the pump on the line 1-1 of Fig. 3.

Fig. 2 is an end view of the pump with the end cover plateremoved.

f Fig. 3 is a section through the pump on the line 3 3 of Fig. 1.

Rotor a is splined on a shaft c extending through a housing b. The rotor has slots through 'which wings or vanes d extend into the air com- -36 pression space between rotor and housing and into contact with the inner circumferential wall of the' housing, these vanes sliding toward and from the shaft in the rotation of the rotor, which is'eccentrically disposed with relation to the housing. '40 Keyed to the shaft c is a-driving pulley e.

, In each end wall of the housing is an internal recess in which is fitted a shaft bearing. The

' bearing f nearest the driving pulley is preferably of the roller type This construction allows lproper oiling of the space and contact with theV while the other bearing o isv '45 preferably of the ball type.

bearings, and if it'does not necessarily exclude some leakage beyond disc k, any oil leaking therethrough will not escape to the outside of the pump, as hereinafter explained.

Beyond bearing g shaft c extends into an end chamber n closed by an end plate o. The end of the shaft that projects into chamber n carries a pinion p which engages a gear wheel r on a counter-shaft s. The gear wheel has formed on its outer'face an arcuate rib or cam t. Secured 65 to end plate o is a bracket u carrying, insulated therefrom, a contact v, connected with one pole of an electric circuit. Bracket u, which is connected with the other pole of the circuit, carries a pivoted contact arm w. A spring a: normally holds arm w in contact with contact v. During part of the revolution of gear 4wheel r, cam tengages arm w and maintains it out of engagement with contact v. `Thereby the electric circuit is alternatively opened and closed and electric pulsations are transmitted to a milking machine unit (not shown).

While the driving connections from the pump shaft to the electric pulsator form no part of the present invention, the adaptation of the pump to this purpose, when the pump is used to establish a vacuum in a milking machine, is one of its important uses; and the adaptability of the oiling provisions hereinafter. described to the lubrication of the driving means between the pump a5 shaft and the electric pulsator will be apparent from the description to follow.

'Ihe lower part of chamber n functions as an oil reservoir. The housing wall separating this chamber from the interior of the rotor is provided with an opening 10 through which the oil flows from chamber n into the interior of rotor and, when the pump is not in operation, lls the'rotor to almost the level of the shaft c. In the same wall of the housing, above shaft c, are one or more large openings 11 which, together with the opening 12 around the axis in the opposite 'wall ofthe rotor housing, allows free circulation of air through the interior of the rotor from and to the open spaces within the housing beyond the end walls of the rotor chamber. Qne of these openings 11 is extended, at its rear outer edge, at 13, nearly, but not quite, to the inner circumferential wall of the rotor, being less distant than opening 10 from such wall. Thus, the edge of opening 13 nearest the circular inner wall of the rotor may be about one-sixteenth of an inch distant from said. wall. The lower edge of hole 10, which is below and in ver los `tical alignment with the axis of shaft c, may be 11 about three-sixteenthsof an inch distant from said Wall.

Opening to an air-suction pipe (not shown) is an air inlet communicating with a long arcuate air chamber 31. The inner wall of the chamber is a short distance Within the bore of the housing, leaving a narrow elongated arcuate orince 32 for passage of air from chamber 31 to the space between the rotor and housing bore. There may be two of these air chambers connected by a cross passage 33 into which the air inlet 30 directly opens. On the other side is an air outlet 34 from the air space between rotor and housing. This outlet, as shown by the arrow, communicates with the outlet 35 to which is threaded an air exhaust pipe (not shown). The arrangement of air passages forms no part of the present invention and therefore is not required to be shown in more detail and is set forth fully in certain of the prior patents hereinbefore mentioned, e. g., No. 1,637,484.

When the pump is put into operation, centrif ugal force throws the oil in the interior of the rotor out of such interior through the opening 13 into chamber 11.. This operation continues until there is left a film of oil not substantially greater in thickness than the shortest radial distance (which has been assumed to be one-sixteenth of an inch) between the outer edge or opening 13 and the inner wall of the rotor chamber. A fresh supply or cil is, however, continually entering the rotor from chamber n through the opening 10, so that discharge of oil, at a limited rate, from the rotor, proceeds continuously through the opening 13 into chamber n. In order to provide a plentiful supply of oil, the lower part of chamber n, comprising the oil reservoir, is extended in length as shown in Fig. 2, and provided with a mier-opening 14. A sight glass 15 allows visual inspection or the interior.

The above construction insures a continuous circulation of cil and the maintenance of a desired volume ci oil within the rotor chamber.

While escape or" oil from the pump would be impossible if the stumng box were oil-tight, the possibility of leakage of oil through both discs 7c and lc is guarded against by placing the stumng box in the chamber i, hereinberore mentioned, formed on the housing. This chamber communicates with the air compression space of the rotor through a small opening- 20, the preferred location of which is best shown in Fig. S. At this point in the air compression space, there is a vacuum of about two to three inches, and there is consequently a similar low vacuum in chamber i. Atmospheric pressure, therefore, prevents leakage of oil around shaft c through disc lc'. By thus connecting the suction passage 20 from the chamber i with the air compression space of the rotor chamber and at a point where the vacuum is comparatively low, instead of connecting it with the suction side of the pump, leakage of oil is prevented without affecting the volumetric eiciency of the pump.

Having now fully described my invention, what I claim and desire to protect by Letters Patent is:

1. In a vacuum pump, the combination of a pump housing containing a substantially cylindrical rotor chamber having end walls and an adjacent chamber providing an oil reservoir, a driving shaft extending through the pump housing and rotor chamber, a rotor within the rotor chamber and mounted on the shaftv so as to turn therewith, there being an oil discharge opening in an end wall of the rotor chamber the minimum distance between whose outer edge and the inner circular wall of the rotor is relatively small so as to provide a lm of oil within the rotor of limited thickness, and an oil inlet through which oil flows from the oil reservoir to the interior of the rotor to maintain a constant circulation of oil through the interior of the rotor.

2. In a vacuum pump, the combination of a pump housing containing a substantially cylindrical rotor chamber having end walls and an adjacent chamber providing an oil reservoir, a.' driving shaft extending through the pump housing and rotor chamber, and a rotor within the rotor chamber and mounted on the shaft so as to turn therewith, there being an oil discharge opening in an end wall of the rotor chamber the minimum distance between whose outer edge and the inner circular wall of the rotor is relatively small so as to provide a film of oil within the rotor of limited thickness, and an oil inlet opening between the reservoir chamber and the interior of the rotor below said shaft whose outer edge is spaced a somewhat greater distance than the oil discharge opening from the inner circular wall of the rotor.

43. In a vacuum pump, the combination of a pump housing containing a substantially cylin drical rotor chamber having end walls and an adjacent chamber providing an oil reservoir, a driving shaft extending through the pump housing and rotor chamber, and a rotor within the rotor chamber and mounted on the shaft so as to turn therewith, there being an opening in an end wall of the rotor chamber and an oil inlet between said reservoir chamber and the interior or the rotor below said shaft, the outer edge of said oil inlet being spaced a greater distance from the inner circular wall of the rotor than the minimum distance of said opening from the inner circular wall of the rotor, said opening comprising an arcuate slot whose outer end edge is extended outward and through which oil is discharged to maintain a thin nlm o oil on the inner circular wall of the rotor and a constant circulation of oil through the rotor.

4. In a vacuum pump, the combination with a pump housing containing a rotor chamber and another chamber providing an oil reservoir, a driving shaft extending through the pump housing and rotor chamber, and a rotor within the rotor chamber and mounted on the shaft so as to turn therewith, of bearings inside the pump housing between said housing and the shaft, means to circulate oil from within the housing through the rotor and back to within the housing, a driving element secured to said shaft outside the housing, and an auxiliary chamber at the end of the housing nearer said driving element and in communication with the corresponding bearing, there being a passage between the auxiliary chamber and the air compression space of the rotor chamber, said passage being so located as to maintain in the auxiliary chamber a pressure which is subatmospheric but substantially higher than the sub-atmospheric pressure at the intake of the pump.

5. In a vacuum pump, the combination with a pump housing containing a. rotor chamber and another chamber providing' an oil reservoir, a driving shaft extending through the pump housing and rotor chamber, and a rotor within the rotor chamber and mounted on the shaft so as to turn therewith, of bearings inside the pump housing between said housing and the shaft, means to circulate oil from within the housing through the rotor and back to within the housing, a driving element secured tuV said shaft outside the housing, means providing an auxiliary chamber at the end of the housing nearer the driving element.

and in communication with the corresponding bearing, discs within said chamber closely fitting the shatt, and elastic means between. such discs holding the same against the end walls of the last named chamber, there being a 4 passage between the auxiliary chamber and the air compression space oi' the rotor chamber, said passage being so located as to maintain in the auxiliary chamber a pressure which is sub-atmospheric but substantially higher than the sub-atmospheric pressure at the intake of the pump.

6. In a vacuum pump, the combination with a pump housing containing a rotor chamber and another chamber providing an oil reservoir, a driving shaft extending through the pump housing and rotor chamber, and a rotor within the rotor chamber and mounted on the shaft so as to turn therewith, of bearings inside the pump housing between said housing and thel shaft. means to circulate oil from withinvthe housing through the rotor and back to within the housing a, driving element secured to said shaft outside the housing, means providing an 'auxiliary chamber at the end of. the housing nearer the driving element and in communication with the corresponding bearing,

and a stuiiing box in said chamber surrounding the shaft, there being a passage between the auxiliary chamber and the air compression vspace of the rotor chamber, said passage being so located as to maintain in the auxiliary chamber a pressure which is sub-atmospheric but substantially higher than the absolute pressure corresponding to the partial vacuum at the intake of the pump.

CYRUS HOWARD HAPGOOD. 

